300-410 Exam Dumps - Cisco CCNP Enterprise Questions and Answers

After redistribution, R3 learns about network 10.1.1.0/24 via two paths:

+ Internal BGP (IBGP): advertised from R4 with AD of 200 (and metric of 0)

+ OSPF: advertised from R1 with AD of 110 (O E2) (and metric of 20)

Therefore R3 will choose the path with the lower AD via OSPF

But this is a looped path which is received from R3 - > R2 - > R1 - > R3. So when the advertised route

from R4 is expired, the looped path is also expired soon and R3 will reinstall the main path from R4.

This is the cause of intermittent connectivity.

We can solve this problem by denying the 10.1.1.0/24 prefix from being redistributed into OSPF on

R1. So R3 will not learn this prefix from R1.

Or another solution is to place an OSPF distribute-list inbound on R3 to block the 10.1.1.0/24 prefix

from being advertised back to R3.

In this topology, Chicago router (Hub) will receive advertisements from Los Angeles (Spoke1) router on its tunnel interface. The problem here is that it also has a connection with New York (Spoke2) on that same tunnel interface. If we don’t disable EIGRP split-horizon, then the Hub will not relay routes from Spoke1 to Spoke2 and the other way around. That is because it received those routes on interface Tunnel1 and therefore it cannot advertise back out that same interface (splithorizon rule). Therefore we must disable split-horizon on the Hub router to make sure the Spokes know about each other.

R1(config)#int tunnel 1

R1(config-if) no ip split-horizon eigrp 100

A Multiprotocol Label Switching(MPLS) Layer 3 Virtual Private Network (VPN) consists of a set

of sites that are interconnected by means of an MPLS provider core network. At each customer

site, one or more customer edge (CE) routers attach to one or more provider edge (PE) routers.

https://community.cisco.com/t5/other-network-architecture/out-of-band-router-access/td-p/333295

The “transport output none” command prevents any protocol connection made from R1.

Therefore our SSH connection to 192.168.12.2 was refused. In order to fix this problem we can

configure “transport output ssh” under “line console 0” of R1.

Note: The parameter “-l” specifies the username to log in as on the remote machine.

Follow these guidelines when configuring the switch as an SSH server or SSH client:

+ An RSA key pair generated by a SSHv1 server can be used by an SSHv2 server, and the reverse.+ If the SSH server is running on a stack master and the stack master fails, the new stack master uses the RSA key pair generated by the previous stack master

+ If you get CLI error messages after entering the crypto key generate rsa global configuration command, an RSA key pair has not been generated. Reconfigure thehostname and domain, and then enter the crypto key generate rsa command.+ When generating the RSA key pair, the message No host name specified might appear. If it does, you must configure a hostname by using the hostname globalconfiguration command.+ When generating the RSA key pair, the message No domain specified might appear. If it does, you must configure an IP domain name by using the ip domain-nameglobal configuration command.+ When configuring the local authentication and authorization authentication method, make sure that AAA is disabled on the console.

1. R1 received DHCP packet and its interface was configured with the DHCP helper address. But we are not sure if R1 forward DHCP packet to R2 or not. 2. If we connect PC directly to R2 then this problem will not appear - > DHCP Server function was configured on R2.

From these facts, the most likely problem is related to Option 82. Maybe R2 ignored DHCP request packets because it was receiving these packets with the giant field set to 0.0.0.0.

By default Cisco IOS devices reject packets with zero “giaddr” and by default Cisco Catalyst switches use “giaddr” of zero when configured for DHCP snooping! Reference: https://blog.ine.com/2009/07/22/understanding-dhcp-option-82

If we can run the “debug ip dhcp server packet” on R2, we may see these messages:

*Feb 22 23:54:57.759: IP: s=0.0.0.0 (FastEthernet0/1), d=255.255.255.255, len 34 4, input feature, MCI Check(64), rtype 0, forus FALSE, sendself FALSE, mtu 0, fw dchk FALSE *Feb 22 23:54:57.759: IP: s=0.0.0.0 (FastEthernet0/1), d=255.255.255.255, len 34 4, rcvd 2 *Feb 22 23:54:57.759: IP: s=0.0.0.0 (FastEthernet0/1), d=255.255.255.255, len 34 4, stop process pak for forus packet

*Feb 22 23:54:57.759: DHCPD: inconsistent relay information. *Feb 22 23:54:57.759: DHCPD: relay information option exists, but giaddr is zero

We are receiving the DHCP packet from R1, source 0.0.0.0, and destination 255.255.255.255 broadcast, but if you notice from the debug output, R2, our DHCP Server, is complaining that the relay information is inconsistent. Option 82, Information Option, is contained in the packet but the GIADDR is zero. The GIADDR stands for Gateway IP Address, which is the IP Address of the relaying agent. The Option 82, Information Option, would then contain the receiving port and hostname of the Relaying Agent by default.

R2 sees the Option 82 information, signalling that the DHCP packet might have been relayed, BUT there is no relaying IP Address. This is the behavior of DHCP Snooping when enabling it on a switch, and since the switchport does not contain an IP Address, since it’s Layer 2, no GIADDR will be added.

Instead, just the Option 82 Information is added and this is the problem we have, but there are options:

1. You could trust all on R2 the DHCP Server, which will cause the server to not be so suspicious: – ip dhcp relay information trust-all – ip dhcp relay information trusted 2. Disable theaddition of Option 82 information on SW: – no ip dhcp snooping information option 3. Trust the port that is receiving the DHCP Discover: – ip dhcp snooping trust

Any of these options will fix our predicament.

Once again, Cisco changed the IOS configuration commands required for OSPFv3 configuration. The new OSPFv3 configuration uses the “ospfv3” keyword instead ofthe earlier “ipv6 router ospf” routing process command and “ipv6 ospf” interface commands.

The Open Shortest Path First version 3 (OSPFv3) address families feature enables both IPv4 and IPv6 unicast traffic to be supported. With this feature, users may havetwo processes per interface, but only one process per address family (AF).

https://www.cisco.com/c/en/us/td/docs/iosxr/ncs5500/vpn/65x/b-l3vpn-cg-ncs5500-65x/b-l3vpn-cg-ncs5500-65x_chapter_010.html

The ingress PE router must be able to reach the egress PE router for a packet to be relayed to its destination.

HTTP and HTTPs run on TCP port 80 and 443, respectively and we have to remember them.

Syslog runs on UDP port 514 while NTP runs on UDP port 123 so if we remember them we can find out the matching answers easily. But maybe there is some typos in this question as 2001:d88:800:200c::c/126 only ranges from 2001:d88:800:200c:0:0:0:c to 2001:d88:800:200c:0:0:0:f (4 hosts in total). It does not cover host 2001:0D88:0800:200c::1f. Same for 2001:D88:800:200c::e/126, which also ranges from 2001:d88:800:200c:0:0:0:c to 2001:d88:800:200c:0:0:0:f and does not cover host 2001:0D88:0800:200c::1c.